Suman Adhikari

Quinoline based receptor in fluorometric discrimination of carboxylic acids

Summary Quinoline and naphthalene-based fluororeceptors 1 and 2 have been designed and synthesized for detection of hydroxy carboxylic acids in less polar solvents. The receptor 1 shows monomer emission quenching followed by excimer emission upon hydrogen bond-mediated complexation of carboxylic acids. The excimer emission distinguishes aromatic dicarboxylic acids from aliphatic dicarboxylic acids and even long chain aliphatic dicarboxylic acids from short chain aliphatic dicarboxylic acids. The receptor 1 is found to be selective for citric acid with a strong excimer emission in CHCl3. On the contrary, the receptor 2 exhibited less binding constant value and did not form any excimer upon complexation with the same acids under similar conditions. This established the role of quinoline ring nitrogen in binding with the acids.

Six-coordinate cadmium(II) complex containing a bridging dithiolate ligand: synthesis, crystal structure and antifungal activity study

Abstract A mixed-ligand polymeric metal complex of Cd(II) has been prepared by reactions of Cd(NO3)2·4H2O with 1,3-diaminopropane (tn) and potassium salt of 1,1-dicyanoethylene-2,2-dithiolate and characterized on the basis of spectroscopy and single-crystal X-ray diffraction analysis. Single-crystal X-ray diffraction analysis reveals that the Cd(II) complex crystallizes in monoclinic space group P21/n with distorted octahedral coordination geometry. The Cd(II) complex was screened in vitro against fungal pathogens such as Synchytrium endobioticum, Pyricularia oryzae, Helminthosporium oryzae, Candida albicans (ATCC10231), and Trichophyton mentagrophytes by the disk diffusion method. The biological testing data of the primary ligand K2i-MNT·H2O and [Cd(tn)(i-MNT)]n indicate that the complex exhibits fungistatic antifungal activity, whereas K2i-MNT·H2O has no activity. The fungicidal properties of [Cd(tn)(i-MNT)]n showed that the cadmium complex was more bioactive than the parent ligand.

Cd(II) complexation with 1,1-dithiolate and nitrogen donors: synthesis, luminescence, crystal structure, and antifungal activity study

A new luminescent complex of Cd(II) with 1,1-dicyanoethylene-2,2-dithiolate [i-MNT2− = {S2C : C(CN)2}2−] with 1,3-diaminopropane (tn) and 4-methyl pyridine (γ-picoline) as secondary ligands has been synthesized and characterized on the basis of spectroscopy and single-crystal X-ray diffraction analysis. Single-crystal X-ray diffraction analysis reveals that cadmium(II) is five coordinate in a 1-D polymer. Biological screening effects in vitro of the synthesized complex has been tested against five fungi Synchytrium endobioticum, Pyricularia oryzae, Helminthosporium oryzae, Candida albicans (ATCC10231), and Trichophyton mentagrophytes by the disk diffusion method. A comparative study of inhibition zone values of K2i-MNT·H2O and {[Cd(tn)(iMNT)(4-MePy)]·4H2O}n (1) indicates that the complex exhibits antifungal activity, whereas K2i-MNT·H2O became silent on S. endobioticum, P. oryzae, H. oryzae, C. albicans (ATCC10231), and T. mentagrophytes. Graphical abstract A new luminescent complex of Cd(II) with 1,1-dicyanoethylene-2,2-dithiolate [i-MNT2− = {S2C:C(CN)2}2−] has been synthesized and characterized on the basis of spectroscopy and single-crystal X-ray diffraction analysis. Single-crystal X-ray diffraction analysis reveals that the cadmium(II) complex is five coordinate in a 1-D polymer. Biological screening in vitro of the complex has been tested against five fungi Synchytrium endobioticum, Pyricularia oryzae, Helminthosporium oryzae, Candida albicans (ATCC10231), and Trichophyton mentagrophytes by the disk diffusion method. The antifungal activity of the complex of Cd(II) is significant compared to K2iMNT on S. endobioticum, P. oryzae, H. oryzae, and T. mentagrophytes and proved to be crucial for the growth-inhibitor effect.

Synthesis, crystal structure, and antifungal activity of a newly synthesized polymeric mixed ligand complex of Zn(II) with 1,1-dithiolate and nitrogen donors

A new mixed ligand complex of Zn(II) with 1,1-dicyanoethylene-2,2-dithiolate [i-MNT2− = {S2C:C(CN)2}2−] and 1,3-diaminopropane as ligands has been synthesized and characterized on the basis of spectroscopy and single-crystal X-ray diffraction analysis. Spectroscopic studies and single-crystal X-ray diffraction analysis reveal that the zinc(II) complex is tetrahedral and adopts a 1,3-diaminopropane-assisted linear polymeric assembly. The molar conductance data of the complex in DMF solution show non-electrolytic nature. Biological screening effects of the complex in vitro have been tested against five fungi Synchitrium endobioticum, Pyricularia oryzae, Helminthosporium oryzae, Candida albicans (ATCC10231), and Trichophyton mentagrophytes by the disk diffusion method. A comparative study of inhibition zone values of the primary ligand K2i-MNT·H2O and its synthesized complex indicates that the complex exhibits a fungistatic antifungal activity whereas K2i-MNT·H2O does not affect P. oryzae. Graphical Abstract Complex of Zn(II) with 1,1-dicyanoethylene-2,2-dithiolate [i-MNT2− = {S2C:C(CN)2}2−] and 1,3-diaminopropane.

Reaction mechanisms with loosely bound nuclei {sup 7}Li+{sup 6}Li at forward angles in the incident energy range 14-20 MeV

Emission of charged particles from the {sup 7}Li+{sup 6}Li reaction at E({sup 7}Li)=14-20 MeV is studied at forward angles. Analysis of the inclusive spectra are performed in terms of the statistical model for compound nuclear process and Serber model for inclusive breakup reactions. Compound nuclear calculations better reproduce the experimental data in comparison to the projectile breakup calculations even at extreme forward angles and above barrier energies.